1. Field of the Invention
The present invention relates to a straddle type four-wheeled all-terrain vehicle and, more particularly, to a straddle type four-wheeled all-terrain vehicle with a variable-speed V-belt drive which is disposed on a side of a crankcase of an engine.
2. Description of the Related Art
In a straddle type four-wheeled all-terrain vehicle with a variable-speed V-belt drive covered with a v-belt drive cover, a V-belt, a drive pulley and a driven pulley included in the variable-speed V-belt drive must be cooled by forced cooling. A conventional cooling mechanism forms a cooling air inlet and a cooling air outlet in the v-belt drive cover, and uses the drive pulley or the like with cooling fins of the variable-speed V-belt drive as a tan rotor to ventilate a space covered with the V-belt drive cover. The cooling air outlet is connected to a cooling air exhaust duct. The cooling air exhaust duct is extended under a seat to a position behind the seat to avoid exposing the rider to the cooling air.
On the other hand, as shown in FIG. 9, a cooling mechanism for a variable-speed V-belt drive, disclosed in JP-A 110813/1998 includes a cooling air exhaust duct 211 connected to a rear end part of a V-belt drive cover 200, curved so as to extend upward behind an engine and opening into a space under a seat 210. More specifically, the V-belt drive cover 200 is provided with a cooling air inlet 201 and a cooling air outlet 202 in a front part and a rear part thereof, respectively. A suction duct 206 has a lower end connected to the cooling air inlet 201 and an upper end opening into a space around the lower end of a steering shaft under a front fender 205, and extends upward from the cooling air inlet 201 of the V-belt drive cover 200. A rear segment of the cooling air exhaust duct 211 connected to the cooling air outlet 202 is curved so as to extend upward behind the engine and has an upper open end 211a opening forward into a space under the seat 210.
The straddle type four-wheeled all-terrain vehicle runs about frequently on rugged ground, roads pitted with puddles and seashore. Therefore, the cooling air exhaust duct of the former cooling mechanism extending at a low level beyond the rear end of the seat is liable to be collided with stones and the like. Moreover, mud and water is liable to enter the cooling air exhaust duct through an air outlet thereof.
A rear segment of the cooling air exhaust duct 211 of the latter cooling mechanism shown in FIG. 9 extends upward behind the engine. Therefore, the engine places restrictions on the position of the cooling air outlet 211a of the cooling air exhaust duct 211. Moreover, the rear segment extending behind the engine places restrictions on the arrangement of accessories behind the engine.
Since the upper open end 211a of the cooling air exhaust duct 211 opens toward the front, cooling air is discharged forward against wind. Therefore, hot cooling air is liable to flow around the rider""s foot to spoil riding comfort.
Accordingly, it is an object of the present invention to prevent mud and water from entering a cooling air exhaust duct connected to a V-belt drive cover covering a variable-speed V-belt drive of a straddle type four-wheeled all-terrain vehicle, to avoid spoiling riding comfort by discharged cooling air, and to secure a space for installing accessories behind the V-belt drive cover.
According to the present invention, a straddle type four-wheeled all-terrain vehicle comprises: a body frame; an engine mounted on the body frame and disposed between front wheels and rear wheels, the engine having a crankcase; a variable-speed v-belt drive disposed on a side of the crankcase and covered with a V-belt drive cover, the V-belt drive cover having an upper wall provided with a cooling air discharge port, the cooling air discharge port opening upward; and a cooling air exhaust duct disposed within a right-and-left width of the body frame, the cooling air exhaust duct communicating with the cooling air discharge port, the cooling air exhaust duct having an air outlet located in front of a seat so that a cooling air is discharged through the air outlet into a space under the seat.
Accordingly, the air outlet of the cooling air exhaust duct is positioned at a high level and is surrounded by the engine and the seat, so that mud and water are prevented from entering the cooling air exhaust duct. Therefore, the cooling air discharged from the cooling air exhaust duct can quickly flow rearward under the seat without flowing toward the rider""s foot, and hence cooling air can be prevented from spoiling riding comfort. Since the cooling air discharge port is formed on the upper wall of the V-belt drive cover so as to open upward, a space behind the V-belt drive cover can be effectively used.
Preferably, the engine is a two-cylinder v-engine having a front cylinder and a rear cylinder. The air outlet of the cooling air exhaust duct is located in front of a space between the rear cylinder and the seat so as to discharge the cooling air into the space.
Accordingly, a space in the body frame can be effectively used to form a cooling air exhaust passage for the variable-speed V-belt drive even though the front and the rear cylinders of the two-cylinder v-engine are arranged so as to extend back and forth.
Preferably, the straddle type four-wheeled all-terrain vehicle further comprises a connecting duct interposed between the cooling air discharge port of the V-belt drive cover and the cooling air exhaust duct, the connecting duct being detachably connected to the cooling air discharge port and the cooling air exhaust duct.
Accordingly, parts, such as spark plugs, of which accessibility is degraded by being covered with the connecting duct, can be easily inspected only by removing the connecting duct without removing the cooling air exhaust duct even though the air outlet of the cooling air exhaust duct is disposed in front of the space between the rear cylinder and the seat.
Preferably, the straddle type four-wheeled all-terrain vehicle further comprises a baffle plate connected to the air outlet of the cooling air exhaust duct and extending substantially along an upper surface of the rear cylinder so as to form a cooling air exhaust passage between the baffle plate and the seat through which the cooling air flows rearward.
Accordingly, the cooling air discharged from the cooling air exhaust duct can be further smoothly guided rearward, and the leakage of the cooling air which spoils riding comfort can be further effectively prevented.